1. Field of the Invention
The present invention relates generally to medical instruments and methods for their use. More particularly, the present invention relates to the construction of a sheath having radiation-transmitting elements and use of such a sheath in methods for endoscopic viewing and for photodynamic therapy.
Sheaths are tubular devices commonly used for accessing body cavities and lumens for a wide variety of medical purposes. Of particular interest to the present invention, sheaths may be used for providing percutaneous access for fiberoptic viewing scopes in a number of endoscopic procedures, such as laparoscopy, hysteroscopy, arthroscopy, and the like. In such procedures, the sheath is typically introduced together with an internal stylet, where the stylet has a sharpened distal tip which permits percutaneous penetration. The stylet is then removed, and the desired viewing scope introduced through the central lumen of the sheath. Usually, the viewing scope will include glass lensing for viewing and fiber optics for illumination. In some cases, the viewing capability will be provided by a separate fiberoptic component. The need to provide both viewing and illumination components requires a larger viewing scope diameter than would otherwise be necessary for viewing alone. It would be desirable to be able to use a small diameter glass lens or fiber bundle viewing scopes, without the need to include additional fiberoptical capabilities for illumination.
Of further interest to the present invention, sheaths may also be used for introducing fiberoptic instruments for irradiating or illuminating the uterus and other body cavities in connection with photodynamic therapy. For example, sheaths may be used to first introduce a liquid solution having a radiation-activatable substance therein. After the solution is introduced, a fiberoptic device may be introduced through the central lumen of the sheath in order to irradiate the body cavity and induce the photodynamic therapy. It would be desirable to provide improved sheaths for this purpose which eliminate the need to separately introduce a radiation-transmitting device to illuminate or irradiate the body cavity.
For these reasons, it would be desirable to provide improved sheaths for accessing body cavities and lumens for the purposes of illumination, viewing, photodynamic therapy, and the like. In particular, it would be desirable to provide sheaths having the capability of transmitting light and other radiation wavelengths therethrough for illumination and photodynamic therapy. Such sheaths should incorporate radiation-dispersive tips which can substantially uniformly emanate radiation at the desired wavelength throughout a major portion of the body lumen or cavity. Such sheaths should also be of relatively simple construction, should be economic to fabricate, and should be compatible with conventional stylets in order to permit percutaneous introduction in a conventional manner.
2. Description of the Background Art
U.S. Pat. No. 4,768,858, discloses a hollow fiberoptic tube which can be introduced to a body lumen over a guidewire. The distal end of the tube is shown to be a flat annulus. A number of very early patents show speculums having internal illumination means. See, e.g., U.S. Pat. Nos. 300,525; 951,285; and 1,286,083. U.S. Pat. Nos. 2,843,112 and 5,167,387 describe endoscopes having self-illumination means. U.S. Pat. No. 3,146,775 describes a speculum having light transmitting fibers along its inner surface. U.S. Pat. No. 5,394,863 describes a cervical cup composed of a light transmitting material for illuminating the vaginal fornix during surgical procedures. U.S. Pat. No. 4,834,093 describes a catheter having a light transmitting fiber for focusing light to ablate lumenal obstructions. The use of photodynamic therapy for treating gynecological conditions is described in Wyss et al., (1995) Hum. Reprod. 10:221-226. A solid light fiber having a conical tip for directing light outward at a 90.degree. angle is described in U.S. Pat. No. 5,354,293.